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 Post subject: ImmunoCAP testing
PostPosted: Tue Jan 22, 2008 10:05 pm 

Joined: Thu Nov 10, 2005 10:02 am
Posts: 116
Location: Gatineau
Hi everyone,

I started with a new family doctor today - she's great, and her son has allergies as well! I haven't had allergy testing in a few years, so she referred me to an allergist (I'm new in the area) and told me about something called ImmunoCAP testing. Apparently it costs around $15 per test, rather than being free like the usual skin prick test.

The way she described it is that it's a blood test that counts the specific levels of IgE in the blood reacting to a substance (I might be messing this up). Anyway, this test is a much more accurate way of indicating exactly HOW allergic somebody is to a particular substance, and so they can monitor the levels over the years. Her son, for example, has increasingly lower test levels to eggs, so she suspects his egg allergy will fade over time. His nut allergies are consistently through the roof, though.

While this seems like an interesting concept, and I'm always open to more information, it seems a little scary... and though it would be encouraging to see an allergy fading, I feel as though I already "get" that I cannot have nuts, etc. Do I really need to have sky-high levels from this test to remind me? I feel like it could tip the delicate paranoia/safety balance I have established in my life :)

Does anyone have any experience with this kind of testing, and what perspective did you take on it? Here's some info I found online from what looks like the manufacturer:

ana to peanuts, nuts, eggs, shellfish, bananas
mild asthma and eczema, seasonal allergies

 Post subject:
PostPosted: Thu Jan 24, 2008 12:18 am 

Joined: Mon Jul 03, 2006 8:23 pm
Posts: 190
Hi! I had ImmunoCAPs done a few years ago. I had many low positives and a few very high results. I also had a few moderate-to-high results. Here are my experiences, but please take what I write with a grain of salt. I'm a layperson, albeit one who has had a lot of experience with allergy and allergy testing.

I have anaphylaxis to peanuts. It is full-blown, rapid, and severe. However, my ImmunoCAP result for peanut was only 'moderate' to 'high', but not very high. With this in mind, I called the company that made the test to ask them how this was possible. I was told (directly by the company) that although their test is fairly sensitive to the degree of allergic response, this depends on a few factors. If one's clinical history is of anaphylaxis to a food, and it only registers as moderate on the blood tests, it could mean a few things. For example, it could mean that one hasn't been exposed to the allergen in a long time. (Which is true in my case.) The rep. said that I should still consider my allergy to be anaphylactic based on my clinical history and the test result.

In other words, according to them, a low or moderately positive result doesn't rule out anaphylaxis, and if one has positives, it's best to consult with an allergist to consider tests such as food challenges to learn whether in fact you're allergic to that food. A negative is certainly good, and is possibly more telling than a positive, but it doesn't rule out allergy 100% either.

So, were the tests helpful to me? Somewhat. On the other hand, I had a lot of false low-positive results, including many foods that I eat on a daily basis. Skin scratch testing is (in my opinion) just as good in some ways, and of course, it's less expensive.

One really good reason to have the blood test done, though, is if you want to avoid exposure to the allergen. During a skin scratch test, a small amount of the allergen is placed on your arm (or back. . .) The great thing about the blood tests is that this isn't necessary. A vial or two of blood is sufficient to test for many foods.

 Post subject:
PostPosted: Thu Jan 24, 2008 8:28 am 

Joined: Tue Nov 29, 2005 4:04 pm
Posts: 2044
Location: Gatineau, Quebec
My understanding of the blood tests is that they help the allergists see one part of the puzzle, along with skin tests and the patient history.

The blood test does not tell you how allergic you are. It tells you the likelihood of your having a reaction. I think there is a difference. There is no test at the moment that will tell you how severe a reaction will be. So the blood test might be able to tell you if you are likely to react to a particular allergen - but not how severely.

Anyway, my kids get them on a semi-regular basis (at the suggestion of our allergist), and I trust my allergist to consider the results along with the skin tests and history. It is good to have a series of results (for example, every 2 years) to sort of see where the levels are going (up or down). But like I said, it's one piece of the puzzle, but it does not tell the whole story.

Frankly, I think the science of allergy is more like a black art than a science sometimes...


Karen, proud Mom of
- DS1 (12 yrs): allergic to cashews, pistachios, Brazil nuts, potatoes, some legumes, some fish, pumpkin seeds; OAS
- DS2 (1o yrs): ana. to dairy, eggs, peanuts; asthma

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